Method of and apparatus for saturating sheet material



June 10, 1930. KlRSCHBRAUN 1,762,336

METHOD OF AND APPARATUS FOR SATURATING SHEET MATERIAL Filed Sept. 16, 1926 Patented June '10, 1930 .UNITED STATES PATENT OFFICE LESTER KIRSOHBRAUN, OF LEONIA, NEW JERSEY, ASSIGNOB, BY HESNE ASSIGNMENTS, TO THE PATENT AND LICENSING CORPORATION, OF BOSTON, MASSACHUSETTS, A

CORPORATION OF MASSACHUSETTS METHOD OF AND APPARATUS FOR SATURATING SHEET MATERIAL Application filed September 16, 1926. Serial No. 135,961.

This invention relates to a method of and apparatus for saturating absorbent bodies, such for example as felted sheet material, with liquid or liquefied saturants which expand when heated and contract when cooled. As this property is common to practically all liquids, the invention essentially relates to the utilization of thermal expansion and contraction to efiect more complete and thorough saturation of absorbent bodies, particularly where the saturant is relatively thick or viscous. My invention finds an applicatied and illustration in the fabricated roofing industry wherein felted fibrous sheets are saturated or impregnated with a waterproofing compound, such as molten asphalt,

- "pitch, wax or the like. Roofing of th1s type as commonly made comprises a sheet of felted fibrous material formed on a paper-making machine of rag or asbestos fiber or mixtures of these with each other or with other kinds of fiber. The felt sheet is impreg ing-point asphalt to provide an impervious layer or facing which will not run under solar heat. 7

It is desirable to impregnate the body of the sheet as completely as possible since not only is its waterproof qualities dependent to some extent on the completeness of the saturation, but the mechanical stren th of the sheet varies with the amount 0 saturant absorbed. Felt which is saturated accordin to the resent day commercial metho employed in the making of this type of roofing will generally absorb on the average about 20% by Wei ht of water after immersion for 24 hours. y my invention, I effect such a thorough saturation of the felt as to reduce its water-absorption capacity to less than 2%. It is found that when the felt is immersed in molten as halt and allowed to remain, the amount 0 saturant absorbed soon reaches a maximum which is far below the theoretical capacity of the sheet as reflected by the volume of voids or pore spaces. If upon removal from the bath an excess of saturant is left on the sheet and allowed to dry in as the felt cools, a considerably lar er amount of saturant is absorbed. Furt er absorption can be obtained by immersing for a relatively short period, partially cooling the felt with excess saturant on the surface, then briefly immersing a second time, then allowing excess saturant to dry in as the sheet cools.

By choosing suitable periods for the successive immersions and coolings, ordinary roofin felt can be made to absorb a quan tity 0 low melting-point asphalt substantially equal to its theoretical capacity, the total time of immersion being comparatively brief. The interruption in the saturation which allows an interval of cooling between successive immersions appears to have the effect of causing the saturant and residual air within the sheet to contract by cooling and thus to draw or suck into the sheet the saturant on the surface thereof. The next immersion by heating the absorbed saturant and residual air,- expels practically all of the latter and also provides another surface layer of saturant to be sucked in during the cooling. In this way, the saturation of roofing felt with low melting-point asphalt (150 F.) heated to 425 F. or so may be made fpractically complete. The temperature 0 any given bath must depend on the characteristics of the saturant used, and should be of such a degree as to produce the desired fluidity in the saturant. In the manufacture of sheet roofing, however, it is not desirable to have the felt completely filled with low melting-point asphalt, since a coating of high melting-point asphalt on such roofing would be liable to slip under 1 the action of solar heat. In order to anchor the coatin to the fibrous structure therefore I partlally saturate the felt with high melting-point asphalt as follows:--

:After treating the felt in low meltingoint asphalt to wet the fibers therewith, remove the excess from the surface and replace it at once with molten, high meltingpoint asphalt and permlt an mterval of cooling. It is well known that an absorbent bod takes up a liquid with far greater faci 'ty if the body has previously been wet through with the liquid. Thus the high melting-point asphalt which penetrates with difficulty the pores of dry felt, enters more readily if the fibers have been previously wetted with a more liquid asphalt. The contracting saturant sucks in the surface asphalt, and a subsequent immersion in h1 gh melting-point asphalt followed by a period of cooling results in a degree of saturation which is close to the theoretical maximum. In this case, the saturant in the pore spaces to a. considerable depth from the surface is high melting-point asphalt which will hold the usual coating and slate surfacing without slippage. Roofing elements cut and finished from sheet roofing which has been impregnated according to my invention are stronger and more durable than roofing of the same type now in use, are less liable to deterioration under the action of the weather, and thus will retain their good appearance and weatherproof qualities for'a longer time.

To carry out my invention, I have devised a machine for making sheet roofing of S11- perior quality from raw roofing felt. For

a full understanding of this machine, reference may be had to the drawing which illustrates conventionally apparatus, the elements of which are well known in the art.

Referring to the drawing in detail, 20 indicates a sheet of roofing felt which may be supplied from a roll or any other convenient source. The felt is led around aseries of perforated pipes 21,.these pipes being adapted to supply low melting-point asphalt, e. g., 100 to 150 F., at a-high temperature such as 425. Alternating with the pressure pipes 21 are a series of pairs of-press rolls 22 between which the sheet is passed to work the asphalt thoroughly into the fibrous body of the sheet. A receptacle 23 is provided to catch any excess asphalt which may ooze through the sheet or over the edges thereof. The asphalt in the pipes 21 is supplied at a suitable pressure to force the same into the sheet as the latter passes the perforations in the pi es. The heat and pressure of the asphalt rives the air and moisture ordinarily contained in the sheet from the voids and pores thereof and effects a thorough impregnating of the body of the sheet with asphalt. After being impregnated thus, the sheet comin from the last pair of press rolls 22'is passe through a bath of'high melting-point asphalt held in a suitable container '24. This coats the sheet while it is still substantially at the temperature of the asphalt supplied from the pipes 21. The hot coated sheet is then led over a series of drums 25 which are preferably maintained at a temerature above the melting point of either 'nd of asphalt used, but lower than the temperature of the sheet coming from the container 24:.v The sheet is allowed to cool still further by bein passed over a'series of loopin rolls 26. This supplies an interval of coo 'ng suflicient to allow the saturant within the bod of the sheet to contract and thereby to sue into the sheet the coatings of asphalt deposited on the surface as the sheet assed throu h the container 24. The

0001s sheet from t e looping rolls 26 is then in 27 to overflow into the pool 28 and on successively to the last pool. The pool 27 may be supplied as by a pipe 31 with asphalt heated to a temperature of 500 or so, this temperature being reduced by immersion of the cooled sheet into the asphalt through successive steps until the surplus drawn fromthe pool 30 as by a pipe 32 leaves the pool at a temperature of approximately 350. This succession of pools of asphalt at successively lower temperatures first heats the cooled sheet to a comparatively high temperature, thus expelling any residual air and moisture which may have remained in some of the pores after the initial saturating treatment. The sheet in'passing from one pool to the next is successively cooled in the presence of molten, high melting-point asphalt, so'that the resulting contraction of the saturant within the body of the felt again sucks in more of the high meltingpoint asphalt. This step of re-cooling the sheet in the presence of asphalt is carried on further by passing the sheet over a series of looping rolls 33 which expose the sheet to the air and continue the cooling thereof. A

pair of doctors 34 may be supplied to re- This apparatus may comprise the usual coating mechanism as for example a s out 35 through which high melting-point asp alt may be supplied at the usual temperature for coating purposes, the asphalt from the spout being spread as by a roll 36. A coating roll 37 may be provided to coat the underface of the sheet, this roll being supplied with asphalt from the container 38 as by a feed roll 39 which dips thereinto. The container 38 may be supplied by suitable connections with asphalt leaving the tank 30 through the drain pipe 32, this partially cooled asphalt having just the right viscosity for a coating application on the face of the sheet. The level in the container may be maintained as by a suitable overflow pipe. The coated sheets is then surfaced withucomminuted material as desired,

a receptacle 40 with suitable brushes 41 being illustrated for depositing talc or other powder on the under surface of the sheet to make this surface non-sticky. A suitable hopper 42 is shown for depositing crushed slate or equivalent granular mineral on the upper surface of the sheet, a receptacle 43 being provided to catch. any excess which may spill over the edges. It is obvious that, if preferred, both sides of the sheet may be surfaced with slate or both with powder. The sheet is thereupon led over a succession of cooling drums 44 which press the comminuted material into firm engagement with the faces of the sheet and set the coating properly. The finished sheet may then be rolled up for shipment or may be cut into roofing elements of desired shape and size. This method of saturating the raw felt results in anexceptionally thorough saturation thereof, a considerable proportion of the saturant being high melting-point asphalt which is tougher and stronger than the ow melting-point asphalt and does not flow under solar heat. This saturation of the sub-surfaceportions of the felt sheet with high melting-point asphalt enables a firm anchoring of the asphalt coatings to the sheet and results in roofing elements of superior strength and wearing qualities.

Having thus described an embodiment of my invention, it should be evident to those skilled in the art that various changes and modifications may be made therein without departing from its spirit or scope as defined by the appended claims.

I claim:

1. The method of impregnating a fibrous sheet with waterproofing material, which comprises forcing hot waterproofing liquid through the sheet from one side thereof, coating the hot sheet with excess waterproofing liquid, cooling the sheet, applying to the sheet hot waterproofing liquid atp'rogressively diminishin temperatures, and cooling the sheet a secon time.

' asphalt o 2. The method of saturating sheet roofing felt which comprises forcing heat-liquefied asphalt into one face of the sheet, coating the hot sheet with excess asphalt, cooling the sheet, fpassing the sheet throu h molten progressively diminis ing temperature, removing the sheet from the asphalt, and allowing it to cool with excess asphalt on the surface thereof.

3. The method of saturating sheet roofing felt, which comprises wetting the fibers of the sheet with molten low melting-point asphalt, coating the hot sheet with high melting-point asphalt, cooling the sheet, immersingthe sheet successively in pools of molten high melting-point asphalt at successively lower temperatures, and allowing the sheet to cool with excess asphalt on the surface thereof.

4. Apparatus 'for saturating absorbent sheet material with thermolastic compound, comprising means for orcing heatliquefied saturant into the sheet, means for thereafter applying saturant of a different kind to coat both faces of the sheet, means for promoting a cooling of the coated sheet, means for treating the cooled sheet successively with different bodies of hot saturant, and means for again promoting a cooling of the sheet.

5. Apparatus for saturating absorbent sheet material with thermolastic compound, comprising means for orcing heatliquefied saturant into the sheet, means for coating the sheet on both faces with another heat-liquefied saturant, means for promoting cooling of the coated sheet, means for immersing the cooled sheet successively in a series of pools of hot saturant, and means for promoting a cooling of the sheet coming from the last pool.

6. The method of saturating sheet roofing felt, which comprises wetting the fibers of thesheet with heat liquefied asphalt, coating the hot sheet with excess asphalt, cooling the sheet, passing the sheet through molten asphalt of progressively diminishing temperature, removing the sheet from the asphalt, and allowing it to cool with excess asphalt on the surface thereof.

7. The method of saturating sheet roofing p felt, which comprises wetting the fibers of the sheet with heat liquefied asphalt, coating the hot sheet with excess asphalt, cooling the sheet, immersing the sheet successively in pools ofrmolten asphalt, at successively lower temperatures, the asphalt in the first of said pools being at a temperature above that of the sheet, and allowing the sheet to cool with excess asphalt on the surface thereof.

8. The method of saturating sheet roofing felt, which comprises wetting the fibers of the sheet with molten asphalt, coating the hot sheet with excess asphalt, cooling the asphalt on sheet, reheating the sheet with molten asphalt, passing the sheet through pools of asphalt at successively lower temperatures, and allowin the sheet to cool with excess e surface thereof.

9. The method of impregnating a fibrous sheet with 'waterproofin matenal, which comprises wetting the ers of the sheet with liquid low melting-point as halt, coating the sheet with excess liquefie high melting-point asphalt, coolini the sheet, applying to the sheet liquefied igh melting point' asphalt at progressively dlminishing temperatures, and cooling the sheet a second time.

'In testimony whereof I have aflixed'my signature. 7

LESTER KIRSCHBRAUN.

meaaso 

